I was playing a bit of co-op Black Ops around a friend's house this weekend and discovered an awesome little arcade style addition to the zombies mode, which may well have been added a while ago because I haven't played the game in a few months. The regular zombies mode is great fun as well, the multiplayer is dangerously addictive, and the story behind the single player is thoroughly engrossing. Gamestation are currently selling PC copies of the game for £19.98, which'll save you almost £2 on the next best offer coming in from Cool Shop UK.